Toilet and shower (shower head, not dedicated shower) generally are 28' and up. $6000 is generally 23' and down. Sailing is full of conflicts like that. 23' is outboard motors, 28' is getting solidly into inboard engines, big change and cost difference. Then there are the sails, would you buy a used car with a used-up engine? The sails are your primary engine on a sailboat, and sails that have good shape and good life left in them will add to your cost, possibly $2000-3000 for a main and genoa in that size range. Yeah, there goes the budget.
So the less boat and less frills you can make do with, the further your budget will go. If you plan to dock at a marina, they'll probably require liability insurance, add the cost of that. Taking a US Power Squadron course or other basic boating safety course may decrease the cost of that, as well.
And beware the "it just needs a little work" cheapies. A little water damage to the chainplates, deck, or keel structure can turn into a major problem. If you're not familiar with these kind of issues, even on a cheap boat you should have a surveyor or other pro take a look at it to make sure you're not stepping into a quagmire.